Objectives: To study localization, distribution and activity of nitric oxide synthase (NOS) in the human placenta and to speculate the action of nitric oxide (NO) during pregnancy.

• 目的：了解一氧化氮合成酶（NOS）在胎盘中的定位及分布，探讨一氧化氮（NO）在妊娠中的生理病理作用。